THM and MP4

Ok, here’s my deal, I got a new digital camera (Cyber Shot) and when I shot a video it showed up in two ways. .mp4 and .thm Well I opened the .mp4 for it only opened the sound, no video. Is there something I am doing wrong that I don’t know about? Can someone please help me?

What are you opening the mp4 with? QuickTime Player or VLC Media Player shouldn’t have problems playing them.